There is a known technology where an image of a card on which a pattern is drawn is taken with a camera, and an image or a Musical Instrument Digital Interface (MIDI) signal for controlling a musical instrument is output based on the type of the card and/or three-dimensional positional information obtained from the taken image (see, for example, patent document 1).
There also exists a system tool that recognizes a figure on paper with a camera and displays a virtual image on a display of a personal computer (see, for example, non-patent document 1).
Also, there is a known image processing technology that makes it possible to obtain a target image including identification information corresponding to a predetermined image pattern, recognize the identification information from the obtained target image, perform one of pre-registered processes that corresponds to the recognized identification information, display the target image in a predetermined display area, obtain positional information on two or more predetermined positions in he displayed target image, and draw an image corresponding the recognized identification information in an orientation and a position based on the obtained positional information (see, for example, patent document 2).
Further, there is a known digital watermark technology that makes it possible to embed, in a digital content such as a still image, a video, or an audio, information that is different from the digital content and not perceivable by a human being (see, for example, patent documents 3 and 4).